Portable power actuated rim-driven annular saw



Dec. 6, 1949 H. A. CHASE PORTABLE POWER ACTUATED RIM-DRIVEN ANNULAR SAW Filed Oct. 5, 1945 2 Sheets-Sheet l 6, 1949 H. A. cHAsE PORTABLE POWER ACTUATED RIM-DRIVEN ANNULAR SAW Patented Dec. 6, 1949 Henry A. .Chase ',Newtonvlle, fMass., assignor to -Qunimings IMachine Works, Boston, Mass., a

annexation of assachuseiis Application Qctober'u, 1945, 4'Svnerianl No. 629,431

This invention relates -to power lactuated circular saws adapted for .general use but particularly to portable saws for felling and `trin'iming trees and cutting .the wood thereof into suitable lengths, and the general object of the invention is to provide a saw of simple and economical construction Which is .adapted for these and other uses.

More particularly .the object of -the Ainvention is to provide a portable saw of light .weightw-hich can be easily handled and readily .positioned =by an operator horizontally, vertically, or .any desired angle relatively .thereto -so that, for example, a Woodsman can vcut va horizontal slot in one .side of a standing tree, then cut a slot inclinedthereto to provide a notchorker-f and finally .to .cut a slotY in the opposite side of said tree so that the tree will fall in the direction .of the notch .or kerf and which may thereafter be so .positioned -as -to enable the limbs of the tree to be readily Jsevered from the trunk irrespective of .the .direction :in which they project from the trunk, .and nally toenable the trunk -andzlimbs Kto be out into suitable lengths.

Another obgect .of the invention -is to provide a circular saw comprising an annular blade having means engaging the saw blade intermedia-te of itswdth for drivlngthe saw-andjhaving means for maintaining the Isaw accurately in its plane ofl rotation, and means for resisting the thrust of the saw blade during the cutting operation thereof.

Another object of the invention is to provide a portable circular saw of the characterdescribed A having a frame provided with separable 4means .6 ,Qlaims- (Cl. 143-44.)

or sections to enable removal vvand replacement of the saw blade.

More Specfwally one .0f the plaies@ 9i the .avention -to provide a circular saw comprising a 'fiat annular ,Sew blade a trame he ing la heed with oppositely .extending arcuate .arms .Surrounding a .subsiarual ,Segment .,Qf .the man@ .and having Complementary supporting .m ans ensesing 91.1.@ .-fae of .me segment@ .falesie with.

Suitable .spared rotatable .me "b s mounted 1e Sarg fraaie engaging the .opposite .fase gf seid Segment .0f me .blade in. @simular @one firtenmediate .Qf its .Width eating legamenti@ with wegennet ne means i0 meinberlin@ .blade curately in its planeof rotation, meansforv one. Qf .seid .rotatable members .and @emp tar'viniereneaing means bers and -the ular .zone of .the

. ating .the sew `.blade ...ne .eroi/isla@ i with means 'for resistingthe force of thesaw dur;- j

ing its .cutting operation.

ing .supporting means .engaging one .face of said segment .of the blade, a ,driving gear, and gears oppositely spaced ,therefrom mounted on said-` frame to .rotate respectively about axes radialwith respect to .the .axis of rotationof the blade and provided with gears .engaging lthe recesses.

of said .blade voperable -ito rotate Kthe blade vandato counteract 1the force .of thrust .of ythe Ablade during the cutting operation.

A further objectof -t-he .invention is ,to provide l a portable motor .operated saw .with means ,for

supporting lthe saw and .thrusting .it .against .the Work having means .operable by ,a :hand of .the

operator whenso supported to cause .actuation/of the saw .or --to permit .discontinuation .of such .actuation.

These and .other .objects `and lfeatures .of theV 1 invention .will more fully ,appear from the yfollow.- ing descriptionand .the .accompanying drawings and .will bepartiGularlypQinted out in the claims".L

A preferred embodiment .of .the jinvention .is illustrated :in .the caccompanying drawings, lin 1 Which,

Fig. 1 `is a plan viewer-.the saw embodying the invention-.intheact of severing a ,tree .or log and illustrating aninternal combustionmotor adapted todrivethe saw througha .-exibleshaft, a section of which brokenof to .show that it can be of. 1.

any desired length;

Fig. -2 is a sideelevatlon .of .the saw ,and dr,iv. .l ing .mechanism illustrated in Fig. -l in .the act of `felling a tree;

Fig. 3 is a .plan view of the annular saw blade supported in van .arcuate frame, .the upper portion of ywhichand thehandle member extending there? from `is shown zirl-horizontal section ,with the up.-

iper lportion lof one .of the arcuate arms of the frameand the saw therebeneath broken away toshow the mechanism for supporting the .under Side of the saw rblade;

Fia 4 ,is a view y.mainly -in vertical .section .line ,4r-.4 Eig.- 3;.

Fig. 5 isa detail verticalsectional vien/.on line 5-5 .Fig- ShQWiJig fai-1111.911@ eearand cooperative ne tbesar/ accurately 4 mehennm 19.1 me inthe Manent its rotar n .and .caunteracting-the ,forse .of libres@ if ile .Saw during .the .cutting f operation, the construction illustrated in this gure being applicable also to the driving gear and to the companion idle gear;

Fig. 6 is a vertical sectional view on line 5-5 Fig. 1; and,

Fig. 7 is a vertical sectional view on line Fig.1; c" 'ff Fig. 8 is an enlarged kdetail view of the clutch mechanism; and,

Fig. 9 is a detail view of an alternative internally toothed saw.

Fig. 10 is a detail view illustrating the manner in which a motor for driving the saw is mounted directly upon the end portion'of thehandle niember. 1

The mechanism illustrated in the drawings comprises a iiat circular annular saw blade I having peripheral teeth and intermediate of its width a circular series of uniformly spaced narrow approximately rectangular recesses 2 adapted to be engaged by the teeth of a suitable driving gear the inner edge walls of the recesses being substantially concentric with the axis of rotation of the saw blades. The blade is mounted in an arcuate frame surrounding a substantial segment of the blade and having means engaging one face of the blade and a complementary saw supporting member having means engaging the opposite face of the blade, said frame and blade supporting member having cooperating means maintaining the blade accurately in its plane of rotation and means for resisting the thrust of the saw during the cutting operation. The frame comprises a head 3 provided with an outer vertical wall 4 concentric with the axis of rotation and an inner wall also concentric with said axis of rotation surrounding a segment of the saw blade, with in` tegral arcuate outwardly extending arms 6 and 'l terminating in tangential extensions 8 and 9 diverging outwardly. The walls 4 and 5 of the head and the extensions are connected by Webs I and (Fig. 3) to form a light but rigid frame construction. The head 3 desirably is of cored construction having oppositely extending webs I2 and I3 connecting a central preferably cylindrical portion of the head to the outer wall 4. The head 3 is provided with a bore I4 in radial alinement with the axis of rotation |5 of the .saw blade. forming a journal for a shaft I6 which'extends outwardly in a radial direction with respect to the axis of rotation of the saw blade. The head has a rigid tubular extension concentrically surrounding the shaft IE forming a handle member by which the saw as a whole may be supported and applied to the work. For convenience in operation the handle member Il is provided with suitable hand grips, hereinafter described, by means of which the saw may be manipulated to position the saw in any desired relation to the work and also utilized to force the saw blade against the work.

The driving shaft IBhas secured to it suitable collars |8 and |9 adapted to engage suitable shoulders in opposite ends of the journal I4. The driving shaft I6 has secured to it a gear 20 having a hub 2| which engages the adjacent face ofthe saw blade and a collar 22 upon the opposite side of the gear which likewise engages the face of the saw blade. The gear 20 is so constructed as to mesh with the recesses 2 in the saw and each tooth has substantially parallel walls 23 and 24 at the pitch line 25 which is tangential to the saw blade, the tooth converging therefrom -to-its attened and rounded crown, as shown in Fig. 5. 4The end face of each tooth is complementary tothe inner wall of the tooth engaging recesses of the saw blade and is adapted to resist the force of the thrust of the saw during its cutting operation. Similarly the opposite end of each tooth preferably has a face complementary to the outer wall of the toothengaging recesses.

Suitable means are provided for cooperating with the driving gear tomaintain the saw accurately in its plane of rotation. In the preferred construction shown the frame is provided with bosses 26 and 2'| spaced substantially less than apart around the saw blade and preferably at suitably equal distances of 60 on opposite sides of the axis of rotation of the driving shaft. Thrust-resisting gears 28 having hubs 2| and collars 22 engaging the face of the saw blade are mounted on' shafts journaled in said bosses in radial alinement with the axis I5 of rotation of the blade.

The complementary saw supporting member is provided with means cooperating with the driving and cooperating thrust-resisting gears and their hubs to maintain the blade accurately in its plane of rotation The supporting member as illustrated herein comprises an arcuate plate or frame section complementary to the contour of the frame above described having means to engage the other face of the saw and in cooperation with the hubs and collars 2| and 22 of the driving shaft and the hubs and collars 29 of the idle gears accurately to maintain the blade in its plane of rotation.

As illustrated herein the supporting member comprises an arcuate plate or frame section 3| which underlies the segment of the saw blade and desirably is provided withiibre wear plates 32 adapted to engage the adjacent surface of the blade.v The plate 3| has upwardly extending spaced bosses 33 and 34 beneath the arcuate portion of the headv of the frame with extensions 35 upon the bosses 33 and 34 which are pivotally mounted upon a shaft 36 the ends of which are secured in downwardly extending bosses 37 of the head 3 (Figs. 3 and 4) The plate 3| and the outer wall 4 of the arcuate arms are provided with out- .wardly extending lips 38 and 39 respectively which are connected by bolts 4D and 4| preferably provided with winged nuts 42 adapted when removed to permit the bolts to be withdrawn and the supporting plate 3| tobe hingedly swung away from the frame for assemblage and removal of the saw blade therebetween.

By reason of this construction the supporting plate 3| is releasably attached to the frame in such manner to enable itto be swung downwardly to permit the assemblage of the saw within the frame and thereafter swung to the normal position illustrated in Fig. 2 to support the saw in its plane of rotation.

While the supporting member or frame section 3| may be provided in the preferred construction with any suitable means to cooperate with the hubs and collars on the' driving shaft and cooperating thrustresisting gears, suitable rollers 43 and 44 which are'mounted in the supporting member4 or frame section .3| underlie respectively the hubs and.v collars upon these gears and are spaced apart suiiiciently to permit the ends of the teeth` of the respective gears to pass between them. rIIhe rollers 43 and 44 are respectively mounted upon shafts 45 in radial alinement with,

beneath-` maintain the saw accurately infits planeof rotation and: the abutting ofthe inner edge: walls of the respective recesses with theend faces:y of the teeth of the respective driving and coopeerating gears resist the thrust of the saw as it ls-forced against the work- The saw frame is pror vided with suitablel handle mechanism adopted'i to be utilized by the operator tosupport the saw` and to thrust itv against the work duringl the cutting operation. In the preferred constructionA this mechanism comprises the tubular handle member I1 which as above described encloses the' driving shaft I6. The handle member I1 dee sirably is provided with suitably spaced hand gripping members 46 and-41. As illustrated here'- ln the tubular handle member is provided with a:- downwardly extending integral boss 4F which is' located in proximity to the head and the handle member 46 has a yoke-shaped portion 49A which is secured to the boss 48 by suitable bolts 50 In thev construction shown the hand gripping members are of general rectangular form and-de`= sirably are provided with enlarged grips 5| and 52 at right angles-to each other. The otherhand gripis of similar construction having hand` grips 25 53 and 54 at right angles to each other but ther arcuate portion 55 thereof is pivotally connected by a shaft 56 to a boss 5'l extendingdownwardly from the handle member lll and is provided witlr means for actuating a clutch for connecting the' driving shaft of the saw to a shaft driven by a.`v suitable motor.

By reason of the handle construction above describedv the operator While grasping the hand grips 5l and 53 may support the saw in hori' zon-tal position to produce a horizontal slot inl af tree or other vertical piece of work or the saw` may be relatively inclined to the horizontal to-cutI a notch or kerf in the tree which in cooperation' with'l the horizontal cut will determine the direc-f tion in which the tree will be felled.

After the tree has fallen the operator may position thel saw in vertical position to cut o the limbs which extend horizontally or by suitably manipulating the saw by the hand grips 5I and 53, or 52 and 54, position the saw in any desired angular relationto the limb to be severed or to cu`t the trunk of the tree at right angles to its axis whether the trunk is in horizontal position or at an inclination relatively thereto.

The spaced hand gripping members enable' the operator not only to position the saw in different angular relation tor the work but also enable the operator to press the saw blade against the work so that it willcut most effectively.

Inasmuch as the engagement of the rotating teeth of the saw with the work tends to move the" entire saw and saw frame in a direction opposite to the direction of rotation of the sa-w, the savv frame is provided with guiding means to resist s'uch movement. This is accomplished in the present invention by providing a guiding arm 58 which is mounted upon the saw-supporting plate 3| and extends along one of the arcuate arms a distance well beyond the periphery of the saw and which rests against the work and aids in supporting the saw during the cutting operation. In the preferred construction illustrated the guiding' arm 58 has a triangular end portion 59 which underlies the saw-supporting plate 3l and is pivotally mounted adjacent its inner angle upon a bolt 60 which extends through the boss 34a` projecting outwardly from the supporting plate 3l. The guiding arm is adapted to be secured 1n adjusted positions toward and from the axis of rotation of the saw blade l5 by al holtI 6l in#J A arm` 58V to be so adjusted as most effectively to position?7 thev sawfor cutting trees,A limbs; etc., of different sizes Any suitable mechanism may be provided for transmitting power from a suitable` motor to the driving shaft I6A and' preferably comprises means operable by av hand of the" operator while supporting the saw t`o control the' rotation of the saw blade:y For light saws an'- internal combustion motor, electric motor.. or the like', may be mounted directly upon the end portion of the handle mem'-V ber l1 with means adapted to be operated by one of the hands ofthe operator which' support the notor to control` an electric circuit leading to the motor or tol control clutchmechani'sm for releasably connecting a power driven clutch shaft to the driving shaft,. orfl particularly for heavy work', the clutch shaftmay beidriven' by a flexible shaft of any desired length from a more powerfulprefer'ably por-table motor.

.One of the? important features of the invention to providecoupling. means located within' the tubular handle member' operable one2 of the hand grips for coupling and uncoupling the driving shaft I6 for the saw to av shaft which is` driven by a suitable motor.A

A' preferredfform of frictional clutch mechanism is shown in Figs. 3l and 4 of thedrawings and in enlarged detail' in Fig.` 8;

The' driving shaft f6,` having the gear 20 which engages the circular series of recesses' in the saw, has securedY to its opposite end-A a sleeve 621 which is journaled in an irite'n'onal" bearing in the handle member and is provided with an enlarged cylindrical' portion 63 into which arr axially alinedl clutch s'haf-t '5'4" extends A- ring 65, which ts 'within the cylindrical portiinii 63 and abuts against drical portion 65 and tothe clutclr shaft 64 as in usual disk clutch constructions. The outermost disk is engaged by a ring 68 which is' engaged by a cushion spring 69' in its turn engaged by a ring A I0 which is slidably' mounted upon the clutch ShaftA 64=- The opposite" face ofthe ring "lll", whichdesirably is flat; is engaged' by a circular series ofballsl Y'H whichar'e' diametrically oppositely engaged by the inclined face 'l2 of a ring" 'I3 which abuts a shoulder 'I4v upon an'- enlarged section of the clutch shaft 64. A sleeve 15, which is slidv` ably feathered upon the shaft 64 in any suitable manner as by a screw 15 a" nut upon said sleevey having its end seated in' a slot in the clutch shaft, permits longitudinal movement of the sleeve. The' sleeve 15 is provided with a hollow enlarged cylindrical h ead Tl whichslidably fits upon the ring 13 and is provided at its end withan inclined annular wall "I8 which engages the ballsll. The head is' also provided with a cylindrical lip 19 formingy with Athe inclined wall 18 of the headand the inclined face 12 of the ring A13' a ball race for theballs' 1|, The construction is such that when the" had "IT is forced longitudinally of the clutch snaftin the direction toward the work the inclined surface "11 will force the series of balls radiallyl inwardly thereby forcing" the clutch 'lald '67s:v in frictirial engagement which Will rotate the driving shaft. When however the head Il 'l'fs iifo'ved in the opposite direction the balls "l l will thrown outwardly by centrifugal force snoop-suf into engagement'w'ith the lip 19 thereby releasing the disks 61 and 61a: from frictional engagei ment and permitting rotation of the driving shaft and saw to cease. l

Suitable means operable by movement of one of the handle members toward the saw is -provided to cause frictional engagementof the clutch disks and which upon release of such pressure on the handle members will release the disks from frictional engagement. In the construction illustrated an antifriction thrust bearing 80 is interposed between the cylindrical head 11 and the collar 8l. Both bearing and collar are free to rotate about the sleeve 15. The collar 8I is Provided with oppositely extending radial pins. 82 which extend through diametrically opposite slots 83 in the handle member I1 and are journaled in suitable bearings 84 (Fig. 7) in parallel legsV 85 of the yoke-shaped portion 55 of the hand gripping member 41 which are pivotally mounted upon the shaft 56 in the boss 51 which extends downwardly from the handle member I1 as above described.

When therefore the hand gripping member 41 is pressed by the operator in a direction to force the saw against the work the sleeve 15 and its head 11 will be forced in that direction and the inclined surface 18 of the head 11 will crowd the balls 1I radially inwardly thereby forcing the disks.

61 and 61a: into frictional engagement and causing the rotation of the driving shaft I6. When the hand gripping member is moved suiiiciently in the opposite direction the balls 1I will be forced outwardly by centrifugal force thereby releasing the clutch.

Where, as illustrated herein, the driving shaft I6 is driven by a flexible shaft from a motor which is stationary with respect to the portable saw mechanism the clutch shaft 64 desirably is provided with means such as an angular, preferably rectangular, end portion 86 which telescopically engages the complementary socket in a tting 81 which preferably is mounted in antifriction bearings 88 in a casing 89 having a flange 90 which v is bolted to a complementary flange 9| on the end of a tubular handle member I1.

The fitting 81 is flxedly secured to a flexible shaft 92 which is enclosed in a suitable flexible I rectly on the end of the handle member, as heretofore described, a suitable casing containing themotor and the necessary reduction gearings-properly to drive a countershaft having a fitting for coupling it to the clutch shaft may be provided with means for securing the motor casing directly to the flange 9| on the-end of the handle.

As illustrated in Fig. 10 an internal combustion Y motor, such as that shown in Figs. 1 and 2, is provided with a housing 96 enclosing the motor, its

shaft 95 and the reducing gears 94 for driving 4 the shaft 91 which actuates the clutch shaft with the shaft 64 projecting beyond the casing. .The end of the countershaft 91 like that heretofore described is provided with a fitting having an angular, preferably rectangular, socket to t the angular end portion of the clutch shaft. The

housing 96 is provided with a tubular extension.

98 which surrounds the shaft 91 and isprovided with`a flange' 99 complementary to the ange 9I on the end of the handle member I1 and is secured thereto by equally spaced bolts or machine screws (as illustrated in Figs. 3 and 4).

Where the motor is thus mounted upon the end of the handle its weight serves to counterbalance the weight of the saw frame and saw when the assemblage is supported by the hand-gripping members, the motor of course being so positioned on the end of the handle as to be in a vertical position either when the saw frame is horizontal for cutting dow-n a tree or when in a vertical position for sawing horizontal articles such as limbs, etc.

In the operation of the saw in felling a tree the saw is held by the operator in horizontal position with the right and left hands respectively gripping the hand grips 5I and 53. As the saw is moved toward the tree the natural movement of the hand which grasps the hand grip 53 moves it toward the tree and also toward the hand which grasps the hand grip 5I. Such movement of the hand grip 53 causes longitudinal movement of the sleeve 15 in a direction to cause engagement of the clutch members and such engagement of the clutchr members is maintained so long as the saw is .pressed toward the tree to cut a slot into the same. When the saw is withdrawn from the tree the hand gripping member 53 is naturally moved in the opposite direction thereby releasing the clutch and permitting the rotation of the saw to cease. As a matter of fact release of pressure on the hand grip 53 at any time may not result in a release of the clutch members. The clutch is so constructed that the hand grip may be released at any time and the clutch will remain either engaged or disengaged dependent upon the position it happens to be in at that time, and further movement of the hand grip in a proper direction is required properly to engage or disengage the clutch.

In order to minimize the entrance of sawdust or chips into the chamber of the arcuate arms and thus interfering with the proper operation of the idle and driving gears the extensions Il and 9 of the respective arcuate arms and also the complementary extensions of the supporting member are provided with detachable complementary guards 96 and 91 which engage opposite faces of the saw blade and are provided with complementary recesses 98 and 99 through which the teeth of the saw pass during its rotation.

While the invention as hereinbefore described comprises a thin annular circular saw blade having external peripheral teeth a saw blade having internal teeth may be employed. Such a saw is illustrated in Fig. 9 and comprises semi-circular saw sections H39 and IDI which are provided with internal saw teeth |02. The saw sections I and IIlI are provided with overlapping portions which are pivotally secured together by a pin or rivet |03 and the diametrically opposite abutting ends of the saw blade are provided respectively with a spring latch |04 adapted to engage a complementary recess in the other section. The blade is provided with a circular series of narrowly spaced slots I06 adapted to be engaged by the driving gear 20, as heretofore described.

When a saw of this character is to be used the section which is not engaged by the gear 29 is unlatched and swung about the pivot ID3 to enable the work to be inserted in the then open saw. After such insertion the saw section which has thus been swung open is returned to and latched casacca Lin operative Aposition to the other saw section and .the saw blade .rotated in the manner heretofore described. In th-isconstruction, as in the other, 'the engagement of the .root portions of the :gear teeth 2.0 absorb the thrust of the saw as the vhandle member is pulled away from the work instead of being pressed toward it as will be readilyunderstood bv those skilled in the art.

.By reason of the constructionabove described and l-the positioning of the -hand grips '52, and 53, '54, at right angles to each other, the saw can be readily Aheld by the operator either in a horizontal position, a vertical position, 'or in any angularly rotated position with respect to the axis of the driving shaft andnmay be tilted in any direction to the vertical which may be desirable to produce a proper cut -upon the work, 'such for example as a downwardly extending diagonal cut to meet a horizon-tal cut Ipreviously made in the tree for producing a notch which will determine the direction in which the tree was falling, or in any position which may be required properly to sever -a limb from the tree or to make a desired out in any piece of work irrespective of its position.

While the hand gripping members illustrated and 'described herein are 'provided with handles extending at right angles to 'each other, it will be obvious that adjustable hand gripping members may be so secured to the handle member l1 as' .properly to hold the saw in any desired radial position with respect to the axis of the driving shaft I6.

It will be understood ythat the preferred embodiment of the invention disclosed herein is of an villustrative character and not restrictive of the meaning and scope of the following claims.

Having Vthus described the invention, what is claimed as new and desired to be secured by Letters Patent is: v

l. yA circular saw comprising a iiat annular sawl blade having intermediate of its width a circular series of uniform narrowly spaced gearteeth-receivingrecesses with inner walls substantially concentric with the-axis of rotation of lthe saw blade, a frame having a head with oppositely extending portions enclosing a semi-circular segment of the blade, means for maintaining the blade accurately in its plane of rotation, means for driving the blade, thrust-resisting gears spaced substantially less than 180 apart around the enclosed segment of the blade and rotatable about axes in radial alinement with and perpendicular to the axis of rotation of the blade and having teeth provided with faces to engage the inner Walls of said recesses cooperating to resist the force resulting from the action of the exposed active cutting portion of the blade of the saw upon the work produced by manually applied thrust of the saw toward the work.

2. A circular saw comprising a fiat annular saw blade having intermediate of its width a circular series of uniform narrowly spaced gearteeth-receiving recesses with parallel inner and outer walls substantially concentric with the axis of rotation of the saw blade, a frame having a head with oppositely extending portions enclosing a semi-circular segment of the blade, saw-supporting means pivotally mounted on said head, means for releasably connecting said saw-supporting means to said frame, cooperating means on said frame and said saw-supporting means to maintain the blade accurately in its plane of rotation, means for driving the blade, thrustresisting gears mounted on said frame and spaced `.s ii-bstantial'ly less' than 180 apart around the enclosed `segment of the blade and rotatable about axes in radial alinement with and perpendicular to the axis of rotation of .the blade and having teeth provided with faces adapted to engage said walls of said recesses cooperating to resist the .force .resulting from the action of the exposed active cutting-portion of, the blade of the saw upon thework lproduced by manually applied thrust of the saw toward the work.

-3. In a circular saw comprising a iiat annular saw blade having intermediate of its width a circular series lof uniform narrowly substantial-1y .rectangular gear-teeth-receiving recesses having inner and outer walls substantially concentric with the axis of rotation of the saw blade, a frame having a head with oppositely extending portions enclosing a semi-'circularfsegment of the blade, adriving-.shaf-t mounted on said head 'in radial alinement with and perpendicular to the axis -o f rotation of the blade, a gear secured to said shaft `having vteeth meshing with said lrecesses in the blade, handle means extendingoutwardly and radially of said frame and blade as well as parallel with said driving shaft for pressing the saw against the work in the axial direction of the driving shaft, thrust resisting gears mounted on said frame on opposite sides -of said driving-gear spaced substantially less than apart around the enclosed lsegment 'of said saw blade having teeth meshing with said recesses in the sawblade and having faces to engage the inner and outer walls of said recesses cooperatingto resist the force resulting from manually applied ,force pressing the saw toward the work and the force resulting from the action of the exposed act-ive cutting portion of the blade of the saw -upon the work' and cooperating antifriction -meansfor lmaintaining the saw accurately -in the plane of its rotation.

4, .A circular saw comprising a flat annular saw yblade having intermediate of its width a circular series of uni-form narrowly spaced substantially rectangular v'gear-teeth-receiving recesses' having inner walls substantially Yconcentric with the axis of )rotation of the saw blade, a frame having a head with oppositely extending arms enclosing a ,substantial seg-mentA of the blade, a driving shaft mounted centrally on said head in radial alinement with-and perpendicular to the axis of rotation of the blade, a driving gear secured to said said shaft having teeth with parallel walls at the pitch line meshing with the recesses in said blade and provided with end faces adapted to engage the inner walls of the respective recesses in the blade, gears mounted on said frame around the enclosed segment of said saw blade and on opposite sides of said driving gear at substantially equal distances therefrom and rotatable about axes in radial alinement with and perpendicular to the axis of rotation of the blade cooperating to resist the force of the sa'w resulting from the action of the exposed active cutting portion of the blade of the saw upon the work, and means for maintaining the saw accurately in its plane of rotation, and means for pressing the saw against the Work in the axial direction of the driving shaft.

5. A portable power actuated saw comprising a flat annular saw blade having intermediate of its width a circular series of uniform narrowly spaced substantially rectangular gear-teeth-receiving recesses having walls substantially ooncentric with the axis of rotation of the saw blade, a frame having a head with oppositely extend- 11 ing arcuate arms enclosing approximately onehalf the circumference of the blade and having diverging extensions projecting beyond the periphery of the blade, a driving shaftmounted centrally on said head in radial alinement with and perpendicular to the axis of rotation of the blade and extending outwardly beyond said head, a gear xedly secured to said Vshaft having teeth meshing with the recesses in said blade, thrustresisting gears spaced substantially less than 180 apart around the blade mounted on said arms on opposite sides of said driving shaft cooperating to resist opposing sawing force on the exposed active cutting portion of the saw blade, and means adapted to be engaged by the operator for forcing the saw against the work, a saw-supporting member pivotally mounted on said head having arcuate arms complementary to those of said head, a pivotally mounted guiding arm extending along and in parallelism with the arm of the frame toward which the teeth of the saw move when cutting and well beyond the periphery of the blade, means for adjusting the guiding arm relatively to the axis of rotation of thev saw properly to position the saw for cutting Work of different dimensions, and means adapted to be grasped by the operator for forcing the saw against the Work.

6. A circular saw comprising a flat annular saw blade having intermediate of its width a circular series of uniform narrowly spaced substantially rectangular gear-teeth-receiving recesses having inner walls substantially concentric with the axis of rotation of the saw blade, a frame having a head with oppositely extending arcuate arms enclosing a segment of approximately one-half the circumference of the blade, a driving shaft jourrialed centrally on said head in radial alinement with and perpendicular to the axis of rotation of the blade and extending outwardly from said head, a gear xedlyvsecured to said shaft having teeth meshing with the recesses in said blade, thrust-resisting gears provided with end faces adapted to engage the inner and outer walls of the respective recesses in the blade, said thrustresisting gears being spaced substantially less than 180v apart around the blade mounted on said arms on opposite sides of said driving shaft cooperating to resist the opposing sawing force on the exposed active cutting portion of the saw blade, and means adapted to be engaged by the operator for forcing the saw against the work, means for maintaining the saw accurately in its plane of rotation, a tubular handle member rigid with said frame enclosing the extension of said driving shaft, a motor driven clutch shaft journaled in said tubular handle member having a Vfrictional clutch releasably connecting it to said driving shaft, a hand gripping member fixedly secured to said tubular member in proximity to said head, a cooperating hand gripping member suitably spaced therefrom pivotally mounted on said tubular member having means engaging said clutch and operable by the natural pressure on the hand gripping member when the saw is moved to vand maintained in engagement with the work to cause driving engagement of the clutch and upon release of such pressure to enable the clutch members to remain in frlctional engagement or to dlsengage the clutch depending upon the position to which the clutch-actw ating hand grip is moved.

HENRY A. CHASE.

REFERENCES CITED The following references are of record in the file of this patent: f

UNITED STATES PATENTS Number Name Date 423,278 Robison Mar. 11, 1890 530,791 Newton Dec. 11, 1894 773,118 Carter Oct. 25, 1904 1,234,690 Pieper July 24, 1917 1,342,213 Hanson et al June 1, 1920, 1,388,186 McCormick Aug. 23, 1921-Y 1,503,723 Strom i Aug. 5, 1924 1,507,245 Nankivell Sept. 2, 1924 1,520,330 Chinn Dec. 23, 1924r 1,588,744 Keane June 15, 1926 1,616,880 Swanstrom Feb. 8, 1927 2,091,827 Mercatoris Aug. 31, 1927 FOREIGN PATENTS Number Country Date 118,846 Great Britain Aug. 14, 1919 402,765 Great Britain Nov. 28, 1933 Certificate of Correction Patent N o. 2,490,255 December 6, 1949 HENRY A. CHASE It is hereby certified that error appears in the printed specification of the above numbered patent requiring correctlon as follows:

Column 10, line 13, after the Word "narrowly" insert spaced;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oiice.

Signed and sealed this 11th day of April, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

